Early warning of marine cooling system failure

Abstract

An early warning system detects the failure of a marine cooling system by monitoring the presence of water within the cooling system so that an alarm is given upon cessation or a severe reduction of water flow therethrough. A water sensing element is inserted within the cooling system preferably within an exhaust system of a marine engine cooled by the cooling system and a detection circuit is connected to the water sensing element. An alarm signal is generated by the detection circuit if insufficient water flow is sensed by the water sensing element. The circuit preferably comprises a darlington amplifier having a power input terminal, a power output terminal and a control terminal. A resistor and a capacitor are connected in parallel between the power input terminal and the control terminal of the darlington amplifier, the water sensing element is connected to the control terminal and an audible or visual or combined audible and visual alarm device is connected to the power output terminal.

What is claimed is: 
     
       1. In a marine cooling system wherein cooling water is drawn from the body of water supporting a watercraft utilizing a marine engine, said water being drawn through a water inlet, circulated to cool said engine, and discharged back to said body of water through an exhaust conduit of said engine, an early warning system for detecting the failure of said marine cooling system comprising: a water sensing element supported within and electrically insulated from said exhaust conduit, said sensing element being exposed within said exhaust conduit and grounded by water within said exhaust conduit, said water serving as an electrical conductor to ground the exposed portion of said water sensing element within said exhaust conduit;   circuit means connected to said water sensing element for generating an alarm signal if water flow is not sensed within said exhaust conduit as indicated by ground being removed from said sensing element due to the rapid drying of said sensing element within said exhaust conduit; and   alarm means responsive to said alarm signal for warning the operator of said watercraft of impending engine overheating upon detection of a lack of water flow in said cooling system.   
     
     
       2. The early warning system of claim 1 wherein electrical power for said circuit means is connected through a contact of an ignition switch for said marine engine whereby said early warning system is self-checking in that the alarm is initially activated when the ignition is turned on to start the engine and then is extinguished as long as water flows properly through said cooling system. 
     
     
       3. In a marine cooling system wherein cooling water is drawn from the body of water supporting a watercraft utilizing a marine engine, said water being drawn through a water inlet, circulated to cool said engine, and discharged back to said body of water, an early warning system for detecting the failure of said marine cooling system comprising: a water sensing element supported within said cooling system;   circuit means connected to said water sensing element for generating an alarm signal if water flow is not sensed within said cooling system by said sensing element, said circuit means comprising a darlington amplifier having a power input terminal, a power output terminal, and a control terminal; and a parallel combination of a resistor and a capacitor connected between said power input terminal and said control terminal; and   alarm means responsive to said alarm signal for warning the operator of said watercraft of impending engine overheating upon detection of a lack of water flow in said cooling system wherein said water sensing element is connected to said control terminal, said alarm means is connected to said power output terminal, and said electrical power is connected to said power input terminal through a contact of an ignition switch for said marine engine whereby said early warning system is self-checking in that the alarm is initially activated when the ignition is turned on to start the engine and then is extinguished as long as water flows properly through said cooling system.   
     
     
       4. The early warning system of claim 3 wherein said marine engine includes an exhaust system and said water sensing element is supported within said exhaust system. 
     
     
       5. The early warning system of claim 4 wherein said water sensing element comprises a threaded fastener having a noble metal head secured into said exhaust system, said fastener being insulated from and sealed into said exhaust system and providing an electrical connection to said noble metal head external to said exhaust system. 
     
     
       6. The early warning system of claim 5 wherein said alarm means comprises a visible alarm device. 
     
     
       7. The early warning system of claim 5 wherein said alarm means comprises an audible alarm device. 
     
     
       8. The early warning system of claim 5 wherein said alarm means comprises a visible alarm device and an audible alarm device.